Fighting depression is an uphill battle and it doesn't just go away on it's own. You need to help her get through this. Besides seeing a therapist, you need to help by stimulating her mind. I'm sure there are some things she used to like to do that she doesn't do anymore. Get her out of the house everyday and start doing those things. Whether its going to the gym, going for a walk, or reading a book. Try finding a class or hobby that you can do together and get lessons. That will give you guys a way to enjoy something together and something to discuss. I'd say she is lucky to have you since you seem concerned and depression can be tough to overcome. When I went through it, I was alone and it got so bad that I gave away all my guns out of fear that I would do something stupid. It's not going to change overnight but you can start helping her out each and every day.